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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

An advanced actuator for high-performance slewing

A conceptual design for an advanced momentum exchange actuator for application to spacecraft slewing is described. The particular concept is a magnetically-suspended, magnetically gimballed Control Moment Gyro (CMG). A scissored pair of these devices is sized to provide the torque and angular momentum capacity required to reorient a large spacecraft through large angle maneuvers. The concept described utilizes a composite material rotor to achieve the high momentum and energy densities to minimize system mass, an advanced superconducting magnetic suspension system to minimize system weight and power consumption. The magnetic suspension system is also capable of allowing for large angle gimballing of the rotor, thus eliminating the mass and reliability penalties attendant to conventional gimbals. Descriptions of the various subelement designs are included along with the necessary system sizing formulation and material.

Downer, James↗
NASA NTRS1994

Concept verification of three dimensional free motion simulator for space robot

In the development of automatic assembling technologies for space structures, it is an indispensable matter to investigate and simulate the movements of robot satellites concerned with mission operation. The movement investigation and simulation on the ground will be effectively realized by a free motion simulator. Various types of ground systems for simulating free motion have been proposed and utilized. Some of these methods are a neutral buoyancy system, an air or magnetic suspension system, a passive suspension balance system, and a free flying aircraft or drop tower system. In addition, systems can be simulated by computers using an analytical model. Each free motion simulation method has limitations and well known problems, specifically, disturbance by water viscosity, limited number of degrees-of-freedom, complex dynamics induced by the attachment of the simulation system, short experiment time, and the lack of high speed super-computer simulation systems, respectively. The basic idea presented here is to realize 3-dimensional free motion. This is achieved by combining a spherical air bearing, a cylindrical air bearing, and a flat air bearing. A conventional air bearing system has difficulty realizing free vertical motion suspension. The idea of free vertical suspension is that a cylindrical air bearing and counter balance weight realize vertical free motion. This paper presents a design concept, configuration, and basic performance characteristics of an innovative free motion simulator. A prototype simulator verifies the feasibility of 3-dimensional free motion simulation.

Okamoto, Osamu↗
NASA NTRS1978

The Annular Suspension and Pointing System

The Annular Suspension and Pointing System (ASPS) is a general purpose mount designed to provide orientation, mechanical isolation, and fine pointing for space experiments. The ASPS consists of two assemblies, the first being a set of two gimbals attached to a carrier spacecraft (e.g., Space Shuttle) and providing coarse pointing, and the second a magnetic vernier pointing and isolation assembly attached to the inner gimbal of the first assembly and providing fine pointing. Discussion of the evolution of this concept, required related technology, and data from analyses and simulations predicting pointing accuracies that allowed the specification of hardware design requirements is presented.

Anderson, W. W.↗
NASA NTRS1982

Multivariable frequency domain controller for magnetic suspension and balance systems

The magnetic suspension and balance system for an airplane model in a large wind tunnel is considered. In this system, superconducting coils generate magnetic forces and torques on the magnetized soft iron core of the airplane model. The control system is a position servo where the airplane model, with six degrees of feedom, follows the reference static or dynamic input commands. The controller design, based on the characteristic loci method, minimizes the effects of aerodynamic and inertial cross-couplings, and provides the specified dynamic response.

Baheti, R. S.↗
NASA NTRS1994

A metabolic cage for the hindlimb suspended rat

Hindlimb suspension has been successfully used to simulate the effects of microgravity in rats. The cage and suspension system developed by E. R. Holton is designed to produce a headward shift of fluid and unload the hindlimbs in rodents, causing changes in bone and muscle similar to those in animals and humans exposed to spaceflight. While the Holton suspension system simulates many of the conditions observed in the spaceflight animal, it does not provide for the collection of urine and feces needed to monitor some metabolic activities. As a result, only limited information has been gathered on the nutritional status, and the gastrointestinal and renal function of animals using that model. Although commercial metabolic cages are available, they are usually cylindrical and require a centrally located suspension system and thus, do not readily permit movement of the rats. The limited floor space of commercial cages may affect comparisons with studies using the Holton model which has more than twice the living space of most commercially available cages. To take advantage of the extra living space and extensive data base that has been developed with the Holton model, Holton's cage was modified to make urine and fecal collections possible.

Evans, J.↗
NASA NTRS2006

Variable-Tension-Cord Suspension/Vibration-Isolation System

A system for mechanical suspension and vibration isolation of a machine or instrument is based on the use of Kevlar (or equivalent aromatic polyamide) cord held in variable tension between the machine or instrument and a surrounding frame. The basic concept of such a tensioned-cord suspension system (including one in which the cords are made of aromatic polyamide fibers) is not new by itself; what is new here is the additional provision for adjusting the tension during operation to optimize vibration- isolation properties. In the original application for which this system was conceived, the objective is to suspend a reciprocating cryocooler aboard a space shuttle and to prevent both (1) transmission of launch vibrations to the cryocooler and (2) transmission of vibrations from the cryocooler to samples in a chamber cooled by the cryocooler. The basic mechanical principle of this system can also be expected to be applicable to a variety of other systems in which there are requirements for cord suspension and vibration isolation. The reciprocating cryocooler of the original application is a generally axisymmetric object, and the surrounding frame is a generally axisymmetric object with windows (see figure). Two cords are threaded into a spoke-like pattern between attachment rings on the cryocooler, holes in the cage, and cord-tension- adjusting assemblies. Initially, the cord tensions are adjusted to at least the level necessary to suspend the cryocooler against gravitation. Accelerometers for measuring vibrations are mounted (1) on the cold tip of the cryocooler and (2) adjacent to the cage, on a structure that supports the cage. During operation, a technician observes the accelerometer outputs on an oscilloscope while manually adjusting the cord tensions in an effort to minimize the amount of vibration transmitted to and/or from the cryocooler. A contemplated future version of the system would include a microprocessor-based control subsystem that would include cord-tension actuators. This control subsystem would continually adjust the cord tension in response to accelerometer feedback to optimize vibration-isolation properties as required for various operating conditions. The control system could also adjust cord tensions (including setting the two cords to different tensions) to suppress resonances. Other future enhancements could include optimizing the cord material, thickness, and braid; optimizing the spoke patterns; and adding longitudinal cords for applications in which longitudinal stiffness and vibration suppression are required.

Villemarette, Mark L.↗
NASA NTRS1992

Computation of magnetic suspension of maglev systems using dynamic circuit theory

Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper.

He, J. L.↗
NASA NTRS1992

International Symposium on Magnetic Suspension Technology, Part 1

The goal of the symposium was to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices. The symposium included 17 technical sessions in which 55 papers were presented. The technical session covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.

Nelson J Groom↗
NASA NTRS1992

International Symposium on Magnetic Suspension Technology, Part 2

In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, a symposium was held. The proceedings are presented. The sessions covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.

Groom, Nelson J.↗
NASA NTRS2002

Airworthiness Qualification Criteria for Rotorcraft with External Sling Loads

This report presents the results of a study to develop airworthiness requirements for rotorcraft with external sling loads. The report starts with a review of the various phenomena that limit external sling load operations. Specifically discussed are the rotorcraft-load aeroservoelastic stability, load-on handling qualities, effects of automatic flight control system failure, load suspension system failure, and load stability at speed. Based on past experience and treatment of these phenomena, criteria are proposed to form a package for airworthiness qualification. The desired end objective is a set of operational flight envelopes for the rotorcraft with intended loads that can be provided to the user to guide operations in the field. The specific criteria proposed are parts of ADS-33E-PRF; MIL-F-9490D, and MIL-STD-913A all applied in the context of external sling loads. The study was performed for the Directorate of Engineering, U.S. Army Aviation and Missile Command (AMCOM), as part of the contract monitored by the Aerothermodynamics Directorate, U.S. Army AMCOM.

Key, David L.↗
NASA NTRS1992

Payload isolation and stabilization by a Suspended Experiment Mount (SEM)

Many Space Shuttle and Space Station payloads can benefit from isolation from crew or attitude control system disturbances. Preliminary studies have been performed for a Suspended Experiment Mount (SEM) system that will provide isolation from accelerations and stabilize the viewing direction of a payload. The concept consists of a flexible suspension system and payload-mounted control moment gyros. The suspension system, which is rigidly locked for ascent and descent, isolates the payload from high frequency disturbances. The control moment gyros stabilize the payload orientation. The SEM will be useful for payloads that require a lower-g environment than a manned vehicle can provide, such as materials processing, and for payloads that require stabilization of pointing direction, but not large angle slewing, such as nadir-viewing earth observation or solar viewing payloads.

Bailey, Wayne L.↗
NASA NTRS1992

Overview of magnetic suspension research at Langley Research Center

An overview of research in small- and large-gap magnetic suspension systems at LaRC is presented. The overview is limited to systems which have been built as laboratory models or engineering models. Small-gap systems applications include the Annular Momentum Control Device (AMCD), which is a momentum storage device for the stabilization and control of spacecraft, and the Annular Suspension and Pointing System (ASPS), which is a general purpose pointing mount designed to provide orientation, mechanical isolation, and fine pointing space experiments. These devices are described and control and linearization approaches for the magnetic suspension systems for these devices are discussed. Large-gap systems applications at LaRC have been almost exclusively wind tunnel magnetic suspension systems. A brief description of these efforts is also presented.

Groom, Nelson J.↗
NASA NTRS1992

Mechanism synthesis and 2-D control designs of an active three cable crane

A Lunar Crane with a suspension system based on a three cable mechanism is investigated to provide a stable end-effector for hoisting, positioning, and assembling large components during construction and servicing of a Lunar Base. The three cable suspension mechanism consists of a structural framework of three cables pointing to a common point that closely coincides with the suspended payload's center of gravity. The vibrational characteristics of this three cable suspension system are investigated by comparing a simple 2-D symmetric suspension model and a swinging pendulum in terms of their analytical natural frequency equations. A study is also made of actively controlling the dynamics of the crane using two different actuator concepts. Also, Lyapunov-based control algorithms are developed to determine two regulator-type control laws performing the system vibrational suppression for both system dynamics. Simulations including initial-valued dynamic responses as well as control performances for two different system dynamics are also presented.

Yang, Li-Farn↗
NASA NTRS2004

Thermally Insulating, Kinematic Tensioned-Fiber Suspension

A salt pill and some parts of a thermally insulating, kinematic suspension system that holds the salt pill rigidly in an adiabatic-demagnetization refrigerator (ADR) is presented. "Salt pill" in this context denotes a unit comprising a cylindrical container, a matrix of gold wires in the container, and a cylinder of ferric ammonium alum (a paramagnetic salt) that has been deposited on the wires. The structural members used in this system for both thermal insulation and positioning are aromatic polyamide fibers (Kevlar(R) or equivalent) under tension. This suspension system is designed to satisfy several special requirements to ensure the proper operation of the ADR. These requirements are to (1) maintain the salt pill at a specified position within the cylindrical bore of an electromagnet; (2) prevent vibrations, which would cause dissipation of heat in the salt pill; and (3) minimize the conduction of heat from the electromagnet bore and other neighboring objects to the salt pill; all while (4) protecting the salt pill (which is fragile) against all tensile and bending loads other than those attributable to its own weight. In addition, the system is required to consist of two subsystems -- one for the top end and one for the bottom end of the salt pill -- that can be assembled and tensioned separately from each other and from the salt pill, then later attached to the salt pill.

Voellmer, George M.↗
NASA NTRS1993

Magnetic bearings: Fifty years of progress

Magnetic bearings are just beginning to be flown in spacecraft systems, but their development spans more than 50 years. The promise of completely noncontacting, unlubricated rotating systems operating at speeds substantially beyond the range of conventional bearings, and with no wear and virtually no vibration, has provided the incentive to develop magnetic bearing technology for many diverse applications. Earnshaw theorized in 1842 that stable magnetic suspension is not possible in all three spatial directions unless the magnetic field is actively controlled. Since that time, researchers have attempted to successfully support spinning rotors in a stable manner. Development of magnetic suspension systems over the past fifty years has included progress on both passive (permanent magnet) and active (electromagnet) systems. The improvements in bearing load capacity, stiffness, and damping characteristics are traced. The trends in rotor size, rotational kinetic energy, and improvements in active control systems capabilities are also reviewed. Implications of superconductivity on suspension system design and performance are discussed.

Swann, Michael K.↗
NASA NTRS2010

Objectives and Progress on Ground Vibration Testing for the Ares Projects

Integrated vehicle ground vibration testing (IVGVT) will be a vital component for ensuring the safety of NASA s next generation of exploration vehicles to send human beings to the Moon and beyond. A ground vibration test (GVT) measures the fundamental dynamic characteristics of launch vehicles during various phases of flight. The Ares Flight & Integrated Test Office (FITO) will be conducting the IVGVT for the Ares I crew launch vehicle at Marshall Space Flight Center (MSFC) from 2012 to 2014 using Test Stand (TS) 4550. MSFC conducted similar GVT for the Saturn V and Space Shuttle vehicles. FITO will perform the IVGVT on the Ares I crew launch vehicle, which will lift the Orion crew exploration vehicle to low Earth orbit, and the Ares V cargo launch vehicle, which can launch the lunar lander into orbit and send the combined Orion/lander vehicles toward the Moon. Ares V consists of a six-engine core stage with two solid rocket boosters and an Earth departure stage (EDS). The same engine will power the EDS and the Ares I second stage. The current plan is to test six configurations in three unique test positions inside TS 4550. Four Ares I second stage test configurations will be tested in Position 3, consisting of the Upper Stage and Orion crew module in four nominal conditions: J-2X engine ignition, post Launch Abort System (LAS) jettison, critical slosh mass, and J-2X burn-out. Position 2 consists of the entire launch stack at first stage burn-out (using empty first stage segments). Position 1 represents the entire launch stack at lift-off (using inert first stage segments). Because of long disuse, TS 4550 is being repaired and modified for reactivation to conduct the Ares I IVGVT. The Shuttle-era platforms have been removed and are being replaced with mast climbers that provide ready access to the test articles and can be moved easily to support different positions within the test stand. Two new cranes will help move test articles at the test stand and at the Redstone Arsenal rail-head where first stage segments will be received in late 2010. The electrical system for TS 4550 also will be upgraded. The Hydraulic Support Systems (HDSs) used for Saturn and Shuttle are being disassembled and evaluated for use during IVGVT. Analyses indicate that the 45-year-old HDSs can be refurbished to support the Ares I IVGT. An alternate concept for a pneumatic suspension system is also being explored. A decision on which suspension system configuration to use for IVGVT will be made in 2010.

Tuma, Margaret L.↗
NASA NTRS2010

Ensuring Safe Exploration: Ares Launch Vehicle Integrated Vehicle Ground Vibration Testing

Integrated vehicle ground vibration testing (IVGVT) will be a vital component for ensuring the safety of NASA's next generation of exploration vehicles to send human beings to the Moon and beyond. A ground vibration test (GVT) measures the fundamental dynamic characteristics of launch vehicles during various phases of flight. The Ares Flight & Integrated Test Office (FITO) will be leading the IVGVT for the Ares I crew launch vehicle at Marshall Space Flight Center (MSFC) from 2012 to 2014 using Test Stand (TS) 4550. MSFC conducted similar GVT for the Saturn V and Space Shuttle vehicles. FITO is responsible for performing the IVGVT on the Ares I crew launch vehicle, which will lift the Orion crew exploration vehicle to low Earth orbit, and the Ares V cargo launch vehicle, which can launch the lunar lander into orbit and send the combined Orionilander vehicles toward the Moon. Ares V consists of a six-engine core stage with two solid rocket boosters and an Earth departure stage (EDS). The same engine will power the EDS and the Ares I second stage. For the Ares IVGVT, the current plan is to test six configurations in three unique test positions inside TS 4550. Position 1 represents the entire launch stack at liftoff (using inert first stage segments). Position 2 consists of the entire launch stack at first stage burn-out (using empty first stage segments). Four Ares I second stage test configurations will be tested in Position 3, consisting of the Upper Stage and Orion crew module in four nominal conditions: J-2X engine ignition, post Launch Abort System (LAS) jettison, critical slosh mass, and J-2X burn-out. Because of long disuse, TS 4550 is being repaired and reactivated to conduct the Ares I IVGVT. The Shuttle-era platforms have been removed and are being replaced with mast climbers that provide ready access to the test articles and can be moved easily to support different positions within the test stand. The electrical power distribution system for TS 4550 was upgraded. Two new cranes will help move test articles at the test stand and at the Redstone Arsenal railhead where first stage segments will be received in 2011. The Hydrodynamic Support systems (HDSs) used for Saturn and Shuttle have been disassembled and evaluated for use during IVGVT. Analyses indicate that the 45-year-old HDSs can be refurbished to support the Ares I IVGVT. An alternate concept for a pneumatic suspension system is also being explored. A decision on which suspension system configuration to use for IVGVT will be made in 2010. In the next three years, the team will complete the updates to TS 4550, upgrade the test and data collection equipment, and finalize the configurations of the test articles to be used in the IVGVT. With NASA's GVT capabilities reestablished, the FITO team will be well positioned to perform similar work on Ares V, the largest exploration launch vehicle NASA has ever built. The GVT effort continues NASA's 50-year commitment to using testing and data analysis for safer, more reliable launch vehicles.

Tuma, M. L.↗
NASA NTRS1995

Mass properties calibration of the NASA Langley low frequency vibration test apparatus

This report presents a description and calibration results of the modified NASA Langley Low Frequency Vibration Test Apparatus. The description includes both the suspension system and the data acquisition system. The test apparatus consists of a 2 inch thick, 21 inch diameter aluminum plate that is suspended from an advanced suspension system using a 40 foot long cable system. The test apparatus employed three orthogonally aligned pairs of Sundstrand QA-700 servo accelerometers that can measure accelerations as low as 1 micro-g. The calibration involved deriving the mass and moments of inertia of the test platform from measured input forces and measured acceleration responses. The derived mass and moments were compared to test platform mass properties obtained initially from measurements with a special mass properties instrument. Results of the calibration tests showed that using the product of the test apparatus mass and the measured accelerations, the disturbance force at the center of gravity (CG) can be determined within 4 percent on all three axes. Similarly the disturbance moments about the X, Y, and Z axes can be determined within 5 percent by using the product of the measured moments of inertia and the angular accelerations about the X, Y, and Z axes.

Javeed, Mehzad↗